To fix an object (usually mechanical) to a working condition in a haphazard way. Also known as doing a MacGyver on it. This can apply to any non working thing, to fix it in a nonconventional way. This term was created during WW2, in reference to the Germans who were referred to as "Jerries" as slang. Allies often came across hastily repaired objects left by the Germans hence the term Jerry-Rig came to be.

Tom Jerry-Rigged that engine so that it burns more fuel than it was designed to.

To fix or put together using non-standard or improvised materials. A derivation of jury-rig, from the nautical term jury mast. This term refers to a temporary mast raised when the normal mast has been lost due to storm or battle. This is probably a short form of injury mast.
Not to be confused with Jerry-built, which refers to an original construction of poor quality.

"Jim jerry-rigged his carburetor open with a paper clip and some aluminum foil"

To put together in a way that works, but is contrary to the “norm” or specific directions (instructions). To put together in an unusual, better or temporary way.

Example One: When I put together the new lock on my door, I broke off a metal shaft inside the lock so it could only be engaged with a key. That way, I can never be accidentally locked out of the house. I told the workmen, "Don't worry about locking me out if I'm not here when you leave, I jerry-rigged the lock, you need a key to lock it".

Example Two: On the drive home, my muffler was dragging on the asphalt. I jerry-rigged it with a piece of wire and gaffers tape so it would stay in place until I had it repaired.